1. Field of the Invention
This invention generally relates to a parallel data communication system, and, in particular, to a node apparatus for use in such a parallel data communication system. More specifically, the present invention relates to a multi-connection, parallel transmission type node apparatus capable of establishing one or more parallel data transmission paths therethrough.
2. Description of the Background
A multi-junction type node apparatus having a plurality of paired input and output channels is well known and disclosed in Japanese Patent Laid-open Pub. No. 58-139543 which corresponds to U.S. Pat. No. 4,516,272 issued to T. Yano on May 7, 1985 and assigned to the assignee of this application, which is hereby incorporated by reference. The multi-junction type node apparatus disclosed in the above-mentioned U.S. patent receives a plurality of input signals at its plurality of input channels and selects the one which has arrived at the node first and thus the input signals are selected on a first-come-first-served basis.
A communication system including a plurality of similar multi-junction type node apparatuses, each of which is capable of establishing one or more transmission paths therethrough, is disclosed in Japanese Patent Laid-open Pub. No. 61-218026 which corresponds to application U.S. Pat. No. 96532, filed Sept. 15, 1987 and assigned to the assignee of this application, which is also hereby incorporated by reference. In accordance with the teachings of this U.S. patent application, there is provided a node apparatus including a plurality of input and output channels which are normally connected through respective connection gates in a stand-by condition. Upon detection of the arrival of a first input signal at one of the input channels, the connection gates of the other channels are disconnected to thereby prevent the occurrence of a loss of a packet. Each node apparatus is so structured that, when one of the input channels has detected the arrival of an input signal for the first time, an active signal is returned to the corresponding output channel.
A communication system defined by using a plurality of node apparatuses proposed in either of the above-mentioned patents is not limited to any specific architecture, such as a loop or star, and it may take any desired architecture or a combination of two or more of any well-known architectures. Thus, such a communication system has a significant flexibility and adaptation and an expansion or contraction of the system can be carried out virtually without limitation. However, the communication systems of the above-mentioned patents are of the serial transmission type so that a conversion between parallel and serial data is required in order to support parallel transmission.